"Therefore . . ." - Crossword Clue, Answer and Explanation

I've seen this clue in the Penny Press, The Times, the King Feature Syndicate, The Telegraph, The Wall Street Journal, the LA Times, The Independent, the USA Today, the Universal, the Sydney Morning Herald, The Mirror, the Evening Standard, The Guardian, the Newsday and The Star Tribune.

'therefore' is the definition.
(synonyms)

This is the entire clue.

(Other definitions for thus that I've seen before include "In this way" , "as indicated" , "an original Christmas gift" , "It follows" , "Therefore, hence" .)

I've seen this clue in the LA Times, the Sydney Morning Herald, the Evening Standard, the Penny Press, The Washington Post, the King Feature Syndicate, the Newsday, the Newsday.com, The Times, The Wall Street Journal, The Independent, the USA Today, The Mirror, The Sun, The New York Times, The Telegraph, the Universal, The Guardian and The Star Tribune.

'therefore' is the definition.
(I've seen this before)

This is the entire clue.

(Other definitions for ergo that I've seen before include "Thus" , "Consequently" , "'Cogito, ---- sum'" , "so philosopher wrote in Latin" , "It follows" .)

I've seen this clue in the LA Times, the Sydney Morning Herald, the Evening Standard, the Penny Press, The Washington Post, the King Feature Syndicate, the Newsday, the Newsday.com, The Times, The Wall Street Journal, The Independent, the USA Today, The Mirror, The Sun, The New York Times, The Telegraph, the Universal, The Guardian and The Star Tribune.

'therefore' is the definition.
('so' can mean 'consequently' or 'therefore')

This is all the clue.

I've seen this clue in the King Feature Syndicate.

"Therefore . . ." (5)